Excerpt from: The Ethical Gourmet by Jay Weinstein
Perhaps no wild food has been more misrepresented than wild mushrooms. Much of what consumers think is drawn purely from nature are actually cultivated products that never even existed in the wild. Other times, they see farm-grown fungi (derived from once-wild species) that never saw a forest floor. Over the last fifteen years, successful cultivation of varieties that had resisted captivity has revolutionized the mushroom-farming world. Search all you want for wild portobello mushrooms. You'll come up empty, because they were developed by breeders. So were their miniature offspring, creminis. Both are variants of the familiar white button mushrooms. Enoki mushrooms, those slender, elegant, wispy white hatpins, trace their origins back to a lab also. The wild species from which they're derived are orange to yellow in color.
While wild shiitakes exist, they're virtually never foraged or sold in America. The cultivated ones are too good and too cheap to justify the hunt. Ditto with oyster mushrooms. Hen-of-the-woods (maitake), bluefoot, and yellow chanterelles are also cultivated now (although there is still a thriving market for truly wild chanterelles of both colors, foraged in fall and winter).
Like truffles, morels—the handsome honeycomb-textured brown cones with a profound, woodsy flavor and aroma—still defy large-scale cultivation. When you see them, they're probably truly wild. The same is true of cepes (called porcini in Italy). Their complex flavor and irregular shapes are dead giveaways that they haven't yet been tamed.
Mushroom farming is an environmentally sustainable form of agriculture that requires almost no pesticide because the product grows so fast. Foraging, however, sometimes takes a toll on the forests where it's done, as huge teams of foragers trample young shoots as they turn the woods upside down in search of black gold like wild morels. Mostly, though, foraging is done on a small scale. I consider both foraged wild mushrooms and cultivated exotic and domestic mushrooms to be sustainable foods, and good choices for the environmentally concerned.